This invention relates to a power supply device with a solar cell, which is used mainly for small electronic calculators.
The conventional small electronic calculator, such as the desk-top type, has generally used a primary battery, such as the dry cell type, for its power supply. More recently, however, solar cells have begun to be widely used for the same purposes.
In the case of those calculators using a primary battery, when the battery's power has been consumed, the battery must then be replaced with a new one. Battery replacement tends to be troublesome and is also uneconomical. A calculator using a solar cell tends to be inoperative in some places where the ambient light level is reduced even slightly; for example, in a room.